No experience of the Exposure flare, but of the fibre flare i can tell you this, it will die at the first hint of moisture, i lost two to thick fog! they were replaced by wiggle and their replacements have been retired after i had to pour water out of the (now very corroded) battery compartments after a ride in some light drizzle.

I have two Exposure Flare's, one on my bike one on the wife's. Never had any issue with them turning off or on. But I can say they are the only rear light I have found that is truly weatherproof. I used to go through a light every three months or so in my search for one that didn't let the water in (Smart. Knog, Cateye etc). They are also incredibly bright and despite the slightly high cost they have paid for themselves by not needing to be replaced.

Opposite to Flaperons experience. I had a fibre flare that was absolutely awful. It was fantastic while it worked but as Bazz says, the slightest hint of moisture and it fails. A very expensive waste of money IMO. I emailed the people that make them to express my disappointment and see if they'd offer to replace it but got absolutely nothing back. I can't remember why I didn't send it back to where ever I bought it, but I ended up just binning it and vowing never to buy anything of theirs again.

I run the Exposure Flash/Flare on my commuter and think they're great. The rear did have some issues with turning on/off randomly but I sent it back (6+ months ago) and it was fixed within a week and hasn't had any issues since.

I've had issues with my Exposure Flash/Flare lights as well including a new set that I ordered online (from Wiggle) which didn't work at all straight out of the box.

They need a bit of tlc sometimes and it's well worth having a back-up light - mine still very occasionally switch off or change from pulse to steady. Cleaning the contacts usually sorts it.

The Fibre Flare is nice but it's not as bright or as focussed. Best place for it is on a rucksack, then it's at the right height to be easily seen. Mine have never had any problems with moisture - if you are having problems like that, wrap the top and bottom bits in clingfilm!

I had both and i wouldn't recommend them to be honest. The exposure flare (and it pains me to say it as i'm a big fan of exposure stuff) proved to be unreliable for me, the threads on the cap cracked, although to exposures credit they did send a free replacement. The Exposure tracer looks like a better option, for not much more money. Fibre flares suffered from water ingress. I currently use a Hope District 3 and a moonshield 60. The hope looks like it will outlast everything else by some margin, the moonshield feels flimsy by comparison but has lasted well so far.

Fibre Flare here. I use the large one and have it running down my seatstay.
Had it for a year and had no issues with water ingress, despite using it for commuting in all weathers.

I think it's a great "be seen" light - especially as it adds so much side visibility. But then I like to run at least two rear lights (one flashing for attention, one constant for distance judgement) plus retro-reflectives.

I've had my Fibre Flare for 4 years with no issue but that's only night road riding so not commuting in all weathers.
On thing to consider is if you have to take the lights off for security then it is a bit off a faff compared to some.

I use both - flare under the saddle (flash mode) and the fibre flare on my rucksack. I thought the together both work pretty well as "being seen" lights but some drivers obviously still can't see me!!! I find both reliable although the exposure flare does need tlc as crazy-legs said.

Another one here that's used both. The Fibre Flare goes on my pannier rack on pulse and I use the Exposure Flare under saddle. When I have the panniers on, I now have a new light on the seatstay - a Knog Blinder Road R. It's the 70 Lumen one and is markedly better than the Exposure. USB charge, seems weather proof and one heck of an output.

The Fibre Flare hasn't really given me any problems, and has good battery life. The Exposure Flare has occasional turn off / mode switches but in the main I guess it's probably been pretty good. Don't even bother with non-rechargables in it though.

I've one of the original 'long' Fibreflares on a seatstay of the winter bike. Love the idea & has worked superbly as an additional source of visibility for several years.

Two issues for me though. After the first winters use one of the rubber brackets had perished. I emailed the distributor on more than one occasion for replacements & had no response. Disappointing but zip ties to the rescue.

Second thing is just today I've got the bike out to find the flare is illuminated. Thought 'maybe I left it on' but then when pressing the on/off switch it went into on mode, then flashing. It seems to have lost its off mode which has now been replaced with a low light mode. Weird. Battery change made no difference. Oh well...

Same as Orangeboy, there appears to be a little corrosion on the battery contact on the little circuit board thing (I'm not up on electrickery stuff) which suggests the seal has finally been breached.

Given how much crap has been thrown up at it over the couple of years then it's no real surprise.

I'll be having another but will probably just keep it for the road bike where the mudguards will keep it dry, not sure I'd have another for off-road use as I don't bother with mudguards. I'll stick with my cheap Knog which is probably just enough for those short stretches of road I use to link stuff up. Or maybe a redeye micro? Any experiences on how these effect battery life on the Joystick?